Process for producing molybdates



Patented July 15, 1924.

UNITED STATES ALAN KISSOCK, LOS ANGELES, CALIFORNIA.

PROCESS FOR PRODUCING MOLYBDATES.

No Drawing.

To all whom it may concern:

Be it known that I, ALAN KISSOCK, a

. citizen of the United States, and a resident of Los Angeles, in the county of Los Angeles and State of California, have made a certain new and useful Improvement in Processes for Producing Molybdates, of which the following is a specification.

The invention relates to a novel, simple and economical process for producing calcium molybdate, such as is used for example as an addition agent in the manufacture of alloy steel.

Objects and advantages of the invention are set forth in part hereinafter and in part will be apparent herefrom to those skilled in the art. The invention consists in the steps, sequence of steps, and processes hereinafter described.

One of the principal objects of the invention is to provide a process whereby there is produced direct from the ore or ore concentrate a finished product suitable for use directly in the steel furnace in the manufacture of alloy steel, and at a great reduction of cost and increase of efficiency over processes heretofore known.

In the heretofore known or practiced processes of producing calcium molybdate as an alloying addition agent, to be added to the steel, preferably directly during the melting and refining of the steel in the furnace, it is usually done by one of two ways or processes.

In one process, wulfenite (lead molyb-' date) is treated with a solution of an alkaline sulphide. The molybdenum is taken into solution as a sodium molybdate, and the lead is converted into an insoluble sulphide, which with any gangue is separated by filtration.

In the case of the other ore of molybdenum, a sulphide called molybdenite, the material is first roasted to an oxide, usually a trioxide. This molybdenum'oxide is then treated with an alkaline solution, such as sodium carbonate, and the molybdenum is taken into solution as a sodium molybdate, which in turn is separated from the insolublegangue by filtration.

In ither process-, a solution of sodium molybdate is first formed. An insoluble melybdgenum compound may then be obtained by precipitation by adding a proper reagent, such for instance as calcium chlo- Ap-plication filed September 19, 1922. Serial No. 589,240.

ride, to this solution and the resulting calcium molybdate recovered by filtration.

The process of the present invention is adapted or designed especially for operating upon the molybdenum sulphide ore, or molybdenite. ThlS ore as produced from commercial deposits seldom carries more than one per cent of the mineral. The usual or any customary flotation process when applied to such ores delivers a concentrate carrying say up to eighty per cent molybdenum sulphide or molybdenite. This concentrate is the customary starting point for the manufacture of any of the marketable forms of molybdenum, such for instance as the calcium molybdate already referred to.

In the present invention only one operation is necessary. The concentrate containing the molybdenite is thoroughly mixed with the proper proportion of some compound of calcium, preferably calcium carbonate, and the mixture is roasted or heated in an oxidizing atmosphere to a temperature which need only be suflicient'ly high to effect the desired chemical change, and which usually need not greatly exceed one thousand degrees centigrade. In practice with a concentrate of about eighty per cent molybdenite, I prefer to employ about fiftyfive pounds of calcium carbonate to about one hundred pounds of the concentrate, although it will be understood that these proportions are merely exemplary and may be Varied as required and desired.

From observation of my process in practice, there are two reactions, the product of the first of these combining instantly and exothermically with the lime, or other calcium compound, so that the two reactions may be said to occur practically simultaneously. These reactions are probably or substantially as follows (1) MoS -i-7()(air):MoOfl-QSO (2) MoO,l-CaO=CaMoO (3) MoO lCaCO :CaMoO,+CO

In the practice of my process, it is preferable though not absolutely essential that a high grade molybdenite concentrate be employed, since otherwise considerable impurities such as iron, silica, etc., remain in the resulting calcium molybdate. It is not difficult, proceeding by known methods, to make a concentrate, the impurities of which are in no way detrimental to the use of calcium molybdate in the steel furnace as an addition agent in the manufacture of alloy steels. The sulphur content of the molybdate and the losses occurring in the conversion are completely controlledby the proportions of lime used.

Other molybdenum compounds could be employed, or produced and employed, although as at present advised, I regard calcium molybdate to be thebest form for ef' fecting the alloying of steel, especially directly in the furnace and during themelting and refining of the steel. For example, an iron molybdate might be employed. Molybdenum tri-oxideunites with the oxides of other metals to form molybdates of the general formula ROMoO when the proper materials are subjected to the necessary conditions of temperature and atmosphere, and the invention in its broader aspects would include such and other equivalents and substitutes or alternatives.

While the invention is primarily intended to cover the production of molybdates by roasting a molybdenum containing material witha compound of the metal calcium, the process and the claims are also intended to cover the production of molybdates by roasting the molybdenum containing material with compounds of metals which are the chemical equivalents of the metal calcium in the type of reaction here involved.

What I claim is 1. The process of producing a molybdate, comprising subjecting a mixture of molybdenum containing material and calcium containing material to an oxidizing roast, whereby to form a molybdate.

2. The process of producing a molybdate,

taining material to an oxidizing roast in thepresence of calcium oxide.

5. The process of producing calcium molybdate, comprising subjecting a molybdenum containing material and a calcium containing material to an oxidizing roast.

6. The process of producing calcium molybdate, comprising subjecting molybdenite to an oxidizing roast in the presence of calcium oxide.

7. The process of producing calcium molybdate comprising subjecting a mixture of molybdenite and a compound of calcium to an oxidizing roast.

8. The process of producing calcium molybdate, comprising subjecting a mixture of molybdenum containing material and calcium carbonate to an oxidizing roast.

9. The process of producing calcium molybdate, comprising subjecting a mixture of 100 parts by weight of 80% molybdenum concentrates and parts by weight of calcium carbonate, to an oxidizing roast, whereby to form calcium molybdate.

In testimony whereof, I have signed my name to this specification.

ALAN KISSOCK. 

